Should you be worried if youâve received the Johnson & Johnson vaccine? Experts say probably not Expert answers about J&J vaccine safety By Kelli Cook | April 13, 2021 at 9:40 PM CDT - Updated April 13 at 10:22 PM MEMPHIS, Tenn. (WMC) - Two locations in Shelby county scheduled to administer Johnson & Johnson vaccines had to switch to Pfizer vaccines instead. The move came as the federal government takes a closer look at potentially serious side effects. âWe are concerned, but not worried,â said Shelby County Health Officer Dr. Bruce Randolph. The CDC and FDA made the recommendation after rare occurrences of blood clots in some patients.